Insights into using plastic waste to produce activated carbons for wastewater treatment applications: A review

This review explores the potential use of plastic waste for the preparation of activated carbons, which can be used as adsorbent materials to remove contaminants from water. Using discarded plastics to synthesize activated carbons has several benefits. Firstly, it helps to reduce the plastic waste burden that ends up in landfills and oceans or dumped on roadsides. Secondly, it creates a potential sector for using discarded plastics to treat pollutants further and approaches a closer circular economy scenario for plastics. Polyethylene terephthalate, tire, and plastic mixtures have been the plastic polymers most studied. The superficial area of activated carbons derived from plastic waste chars varies in a wide range, from 0.1 to 2152 m2/g. KOH seems to be the most widespread activated agent used, and the one that leads to the best textural properties. In general, the adsorption capacities of heavy metals were lower than 300 mg/g. On average, plastic waste chars have higher kinetic rates for adsorbing contaminants of emerging concern (CECs) compared to heavy metals. CECs uptake varies from 2 to 659 mg/g. Although the feasibility of developing porous materials is currently under research with promising results for a successful industrial application, some flaws regarding the granulometry, possible leaching, regeneration ability, and costs, among others, have not been addressed yet.